mfd: 88pm80x: Change chip id definition and detection

Change the chip id definition and detection and then:

1. We no longer need to add PM800_CHIP_XXX for the coming revision.
2. We no longer need to pass driver_data in i2c_device_id as we
   can distinguish the chips from the CHIP_ID register.

Signed-off-by: Chao Xie <chao.xie@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>